Basic kinetic and thermochemical arguments incorporated into calculations modeling the initial stages of the homogeneous pyrolysis of acetylene reveal that the usual assumption of a free-radical mechanism is flawed. The key findings are that updated thermochemistry for ethynyl, vinyl, and propargyl radicals and the inclusion of falloff corrections in radical reactions lead to (1) exceedingly slow decomposition rates below 1300 K, (2) kinetic inert gas effects, and (3) the formation of benzene rather than vinylacetylene or diacetylene, all predictions at variance with experimental observations. On this basis the involvement of vinylidene is proposed.

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A low valent Pb (II) hydride complex with NacNac ligand (NacNac = [ArNC(Me)CHC (Me)NAr] − , with Ar = 2,6−iPr 2 C 6 H 3 ) is predicted to be the best catalyst for CO 2 activation compared to its Ge (II) and Sn (II) analogues, which have been experimentally reported (Jana, A., et al.

Phenolic compounds represent an important category of antioxidants because they help inhibit the oxidation process of organic compounds, while also acting as antiradicals in many biological processes. In this work, we analyze the transfer mechanisms for a set of catechols and resorcinols of a single electron, proton and hydrogen, with the radical peroxyl (˙OOH) and with different electron withdrawing and donating groups as substituents. By using the M05-2X exchange correlation functional within the Density Functional Theory framework combined with the 6-311++G(d,p) basis set, we were able to compute the Gibbs free energies for all mechanisms and compounds. According to the thermodynamic results, the hydrogen atom transfer mechanism was the most favorable. Therefore, this mechanism with substituents -CH and -COH in catechol and resorcinol was analyzed, using the reaction force and reaction electronic flux to characterize the structural and electronic changes that take place during the reaction. Our results show that electron donating groups favor electronic changes along the reaction path, increasing the spontaneity of the hydrogen atom transfer mechanism.